Power pipe tong with torque responsive brake means

ABSTRACT

A power pipe tong having pipe gripping jaws actuated to pipe engaging position by rotation of a fluid motor driven ring relative to a jaw carrying ring which is initially held against rotation by a brake, the rings rotating together after the pipe is gripped, and in which the brake is pressure operated to apply braking friction at a value determined by the torque of the fluid motor to apply maximum braking friction when the gripping means experience least resistance and minimum braking friction when the gripping means experience maximum resistance.

United States Patent Nicolson et al.

[451 Dec.5, 1972 [54] POWER PIPE TONG WITH TORQUE RESPONSIVE BRAKE MEANS [72] Inventors: Garth Fancher Nicolson, Huntington Beach; Carl Alfred Wilms, La Habra, both of Calif.

[73] Assignee: Byron Jackson lnc., Long Beach,

Calif.

[22] Filed: April 16, 1971 [21] App1.No.: 134,655

[52 US. Cl ..s1/57.1s

[51] Int. Cl. ..B25b 17/00 [58] Field of Search ..81/57.15, 57.18, 57.21

[56] References Cited UNITED STATES PATENTS 3,625,095 12/1971 Barnettetal ..81/57.18

3,550,485 12/1970 Dickmann... 3,518,903

..8l/57.18 7/1970 Ham et a1. ..81/57.18

Primary Examiner- -James L. Jones, Jr. AttorneyDonald W. Banner, William S. McCurry and John W. Butcher [57 ABSTRACT A power pipe tong having pipe gripping jaws actuated to pipe engaging position by rotation of a fluid motor driven ring relative to a jaw carrying ring which is initially held against rotation by a brake, the rings rotating together after the pipe is gripped, and in which the brake is pressure operated to apply braking friction at a value determined by the torque of the fluid motor to apply maximum braking friction when the gripping means experience least resistance and minimum braking friction when the gripping means experience maximum resistance.

10 Claims, 11 Drawing Figures PATENTEDIJEB 51912 SHEET 2 OF 6 INVENTORS. 6A em A/Kd so/v e/42 ,4. 1400145 izi POWER PIPE TONG WITH TORQUE RESPONSIVE BRAKE MEANS BACKGROUND OF THE INVENTION In the making up and breaking out of well pipe joints, such as the threaded tool joints of drill pipe and the tapered threaded joints of well casing, it has become the practice to employ power driven tongs to rotate one length or stand of pipe suspended in the well drilling derrick, while the other length of pipe is suspended in the well bore and held against rotation, usually by the rotary table slips, in the case of well casing, and by a back up tong in the case of drill pipe.

Such tongs, generally, have included pipe gripping means including jaws actuated from retracted positions to pipe engaging positions and thenthe gripping means are revolved to rotate the rotatable pipe. Actuation of the jaws to pipe gripping positions is typically caused by rotating an actuator ring or member relative to a jaw carrying ring or member, while the jaw carrying ring is held against rotation by a brake. When the jaws grip the pipe, the actuator ring and the jaw carrying ring revolve as a unit, and overcome the holding brake friction.

If the brake friction is not adequate to hold the jaw carrying ring of such tongs against rotation with the actuator ring until the usual pipe engaging dies of the jaws effectively grip the pipe, the dies may skid about the pipe damaging both the pipe and the teeth of the dies. On the other hand, if the brake means applies such constant braking friction to the jaw carrying ring as to cause the dies to engage the pipe properly, then, the brake friction must be overcome to turn the pipe, requiring higher power drive means. A relatively high die loading is desirable when drill pipe or casing joints are being finally made up at high torque and when drill pipe joints are being initially broken out. Since the jaws of such tongs are self energized, in the sense that the actuator means applies greatest radial load on the jaws when resistance to rotation of the pipe is greatest, the need for high brake friction is reduced when the rotational resistance of the pipe is high. Moreover, during the spinning of the pipe at high speed to thread the joints in and out, the self energizationof the jaws is effective to maintain the gripping action with less brake friction than is necessary to initially grip the pipe, and it is desirable that the high brake friction need not be overcome.

THE PRIOR ART Heretofore, brake means have been provided for pipe tongs of the type referred to above wherein the braking friction could be varied, whereby effective gripping of the pipe by the dies in the jaws could be assured, as disclosed in Letters Patent of the U.S. Pat. No. 3,500,485, granted Dec. 29, 1970, for Power Pipe Tongs With Variable Brake, to Dickmann and Nicolson. Such prior brakes have required personal attention by an operator to vary the brake friction.

SUMMARY O THE INVENTION The present invention relates to a power tong of the type employing a brake to hold the jaw carrying ring against initial rotation with the fluid motor driven ring until the jaws effectively grip the pipe, and wherein the brake friction is controlled as a function of the fluid motor torque or resistance of the pipe to rotation to vary the brake friction so that the friction is high when necessary but low when high friction is not necessary.

More particularly, the brake means involves a fluid pressure operated brake for holding the jaw carrying ring against initial rotation until the jaws grip the pipe, and then resisting rotation of the jaw carrying ring to assure continued gripping of the pipe by the gripping dies.

Such a novel braking means has as its main advantages the preservation of the dies and the pipe, since the teeth of the dies are always properly set in engage-.

ment with the pipe and do not skid about the pipe. Another advantage is that less motor torque is necessary to overcome the brake during spinning of the pipe or when the torque requirement for rotating the pipe is the greatest during final make up or brake out.

The foregoing objectives are accomplished by the provision of pressure responsive means in the brake control system which pressure responsive means are operable by the pressure of fluid supplied to the tong drive motor to increase the brake pressure when motor pressure is low to assure a good grip on the pipe and to decrease the brake pressure when motor pressure is higher during spinning and joint make up and break out operations.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

V BRIEF DESCRIPTION OF THE DRAWINGS I FIG. 1 is a top plan of a power tong made in accordance with the invention, with portions of the housing broken away, to expose the interior structure, with the gripping jaws retracted;

FIG. 2 is a vertical section, as taken on the line 2-2 of FIG. 1;

FIG. 3 is a view corresponding to FIG. 1, but showing the gripping jaws in pipe gripping positions and the actuator means shifted to break out a joint of pipe;

FIG. 4 is an enlarged vertical section, as taken on the line 4-4 of FIG. 2, and showing a typical actuator slide construction;

FIG. 5 is a horizontal section, as taken on the line 5- 5 of FIG. 2, with parts broken away to show the reverse stop and brake means of the invention;

FIG. 6 is an enlarged fragmentary, vertical section, as taken on the line 6-6 of FIG. 5 showing the details of a brake unit;

FIG. 7 is a fragmentary vertical section, as taken on the line 7-7 of FIG. 6, showing the reverse stop means in a make up condition;

FIG. 8 is a view generally corresponding to FIG. 7, but showing the reverse stop means actuated to the break out condition;

FIG. 9 is a vertical section, as taken on the line 9-9 of FIG. 7;

FIG. 10 is a vertical section, as taken on the line 10- 10 ofFIG. 8; and

FIG. 1 1 is a schematic diagram of the control and operating system for the tong.

DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in the drawings, the tong assembly comprises a body or housing I-l defining an opening for a pipe and in which is rotatably supported pipe gripping means G, including a number of circumferentially spaced gripping jaws J, carried by an inner, jaw-carrying ring or .rotatable member 10, and actuatable radially of the assembly from retracted positions, as seen in FIG. 1, to pipe gripping positions, as seen in FIG. 3, in response to rotation of an outer rotative member or cam ring 11, by drive means including one or more drive chains 12, a fluid pressure operated, rotary, chain driving, spinning motor M, and, depending on whether the tong is being used to make up or break out pipe joints, break out actuator cylinder means B0 and a make up actuator cylinder means MU, each of which actuator cylinder means operatively engages a portion or run of the chain or chains 12 between the motor M and the outer ring 11, whereby extension of the respective cylinder means will apply a pull to the respective run of the chain and effect angular movement of the outer ring 11 in one direction or the other, while the motor M or its chain drive shaft is locked by lock means L.

More particularly, as best seen in FIG. 2, the housing H comprises an annular body 20 to which is suitably affixed, as by fasteners 21, a top annular plate 22. Centrally of the plate 22 is a guide ring support 23, attached to the plate 22 by fasteners 24 and having a guide insert 23a defining the open top of the pipe opening 0. A bottom plate 25, affixed to the body 20 by fasteners 26, combines with the body 20 and the top plate 22 to form an annular space in which the inner ring and outer ring 11 are concentrically disposed for rotation.

The annular body supports the outer ring 11 for rotative movement on suitable ball bearings 27. The inner ring 10 is a composite assembly, including an annular central section 28 which defines the pipe opening 0 and has radial windows 29 through which the jaws J are radially reciprocable between retracted and pipe gripping positions. Formed on or otherwise provided on the central section 28 of the inner ring 10 is an outwardly extended flange 28a, at the outer periphery of which are suitable ball or other bearings 30 engaged with a retaining race member 31 attached to the outer ring 11, as by fasteners 32. Thus, it is seen that the outer ring 11 is revolvable within the housing body 20 on the bearings 27 and the outer ring 11 is revolvable relative to the inner, jaw-carrying ring 10 for a purpose which will be later described.

The gripping jaws J are box-like and comprise a top wall 33, a bottom wall 34 and an inner end wall 35, the latter being adapted, as customary, to receive an assortment of die carriers36 having pipe gripping dies 37 removably carried thereby. Further details of the die carriers are not germane to the present invention, and it will be understood that the use of die carriers of different dimensions radially of the pipe opening 0 enables effective use of the tong on pipe of a wide range of diameters. In order to actuate the jaws J to pipe gripping positions, from retracted positions, each jaw has a cam roller 40 joumaled between the top and bottom walls 33, 34 on'a pin 41, or other suitable support, and the outer ring 11 has a cam surface 42 which defines the inner periphery of the outer ring. Such a cam and roller, tong jaw-actuating means is well known, as are other jaw-actuating means responsive to relative rotation of the inner and outer rings of tongs. As is well known in power tongs useful in making up and breaking out pipe joints, without requiring that the tong be rolled over top to bottom, the cam surface 42 is compound, as seen in FIG. 1, for example. This is to say that operable on the roller 40 of each jaw, the cam surface 42 includes a make up ramp 42M and a break out ramp 428 at opposite sides of central portions 43, these latter portions being indented to allow full retraction of the jaws J at the midpoint of the compound cams 42M and 428. The illustrated tong assembly has means for effecting positive retraction of the jaws J, as distinguished from spring loaded retraction, in the form of an outer cam surface 44 having portions which parallel the make up and break out ramps 42M and 42B and a cam follower pin 45 carried by each jaw and engaged with the cam surface 44. a

It will, now be understood that actuation of the jaws J to the pipe gripping positions, fromthe retracted positions, is caused by relative rotation of the inner and outer rings 10 and 11, respectively, and in the embodiment shown, such relative rotation is caused by rotation of the outer ring by the chain means 12 about the inner, jaw-carrying ring 10, in either direction, due to the compound nature of the cam surface 42.

Brake means are customarily provided to initially hold the inner ring 10 stationary, until the jaws J are locked up on a pipe or are being retracted from engagement with the pipe. In addition, reverse stop means are customarily provided to limit reverse relative rotation of the inner and outer rings 10 and 11 to a point at which the jaws are fully retracted and to prevent reclosure of the jaws on the pipe, as might otherwise be caused by continued relative rotation of the inner and outer rings, say, so that the jaw rollers 40 would travel down the make up ramps 42M, during retraction of the jaws J following the making up of a joint, and continue on past the central depressions 43 and up the break out ramps 42B of the cam surface 42. Brake means are herein shown at B, andreverse stop means are shown at RS, the details of both of which will be hereinafter more fully described.

In order to drive the outer ring 1 1, it is provided with sprocket means, including a pair of vertically spaced sprocket rings 50, 50 extending about the outer periphery of the outer ring 11 and affixed thereto for rotation therewith by a number of pins 51 and retaining fasteners 52. Each sprocket 50 is engaged by one of the drive chains 12, and these chains are driven by power operated means now to be described, and including the reversible fluid motor M and the make up actuator cylinder MU and the break out actuator cylinder B0.

Included in the tong body or housing H is a base section 66 for the power means, this base section being suitably secured to a rear portion 61 of the body member 20, as by fastenings 62. A cover plate 63 is provided for the base housing section and is' secured to the latter by fasteners 64. The fluid motor M is suitably mounted on the top plate 63, as by fasteners which engage in a mounting flange 66 of the top plate. To drive the chains 12, the fluid motor M has its output shaft 67 splined or otherwise drivingly connected to a sprocket drive shaft 68 which is journaled in an upper bearing 69 and a lower bearing 70, these bearings being interposed between the sprocket shaft 68 and removable bearing caps 71 and 72 affixed to the housing by respective fasteners 73 and 74.

Fixed on the sprocket shaft 68 for rotation with the latter, as by keys 75, are a pair of drive sprockets 76, 76 which are engaged with the chains 12 to drive the latter in response to the rotation of the motor output shaft 67 in either direction. Disposed between the sprockets 76 on the sprocket shaft 68 and fixed on the shaft for rotation with the latter by the keys is a sprocket shaft locking gear 77 forming part of the locking means L, previously referred to, by which the chains 12 are anchored during final make up and initial break out of a pipe joint. This locking gear has teeth 78 adaptedfor engagement-by complemental teeth 79 on the confronting end of a locking dog 80. The dog 80 is reciprocable between a retracted position and a position at which its teeth 79 mesh with the teeth 78 of the locking gear 77, as generally seen in FIGS. 1 and 3, respectively. Ears 82, 82 formed in the base 60 and having tongue and groove connections at 83, 83 with the dog 80 support the latter for reciprocation, and actuator means, in the illustrated form of a pressure operated actuator cylinder 84 having an extensible rod 85 are adapted to actuate the lock dog or slide 80 between its two positions. Suitable support and anchor means for the actuator cylinder 84 are shown as a yoke member 86 affixed to the ears 82 by fasteners 87 and'to which one end of the cylinder 84 is pivotally connected at 88.

It is now apparent that the fluid motor M is capable of driving the chain drive oppositely, when the lock dog 80 is retracted, to spin the gripping means G of the tong in either direction when spinning up and spinning out pipe joints. In addition, the motor drive, when locked by'the dog 80, anchors the chains 12 so that the runs of the chains between the locked sprockets 78 and the outer ring 11 may be actuated by the actuator cylinder means MU and B0 to also actuate the gripping means G through an arc of motion sufficient and at sufficient torque to finally make up or initially break out a pipe oint.

As seen in FIGS. 1, 3 and 4 to best advantage, the make up actuator cylinder means MU includes a pressure cylinder which has an car 101 at one end pivotally connected or otherwise affixed by a pin 102 to the tong housing H. The cylinder 100 has a fluid connector 103 for the admission and exhaust of pressure fluid. A piston 104 within the cylinder 100 has a'rod which projects from the other end of the cylinder 100 and is connected to a slide block 106 by an enlarged head 107 on the rod 105, seating in and retained in a seat block 108 by a retainer 109 which is fastened to the slide block 106 by suitable fasteners 109a. The slide block 106 rides slidably between a pair of parallel rails 110 which are secured by fasteners 111 to supporting flanges 112 which extend longitudinally within the base 60 of the housing H.

Extending vertically through the black 106 is a sprocket shaft 113 having upper and lower idler sprockets 114 and 115, respectively, mounted for rotation on suitable bearings 116 and 117 which are retained in place by keeper plates 119 and 120 affixed to the shaft ends by respective fasteners 121 and 122. The runs of the chains 12 between the spinning motor sprockets 78 and the outer ring sprockets 50 engage the idler sprockets 114 and 115, and, upon extension and retraction of the cylinder 100 and rod 105, are extended in loops along a plane parallel to the plane of the axes of the outer ring sprockets 50 and the motor sprockets 114 and 115 to avail of the mechanical advantage, as well as to increase the total angular movement of the gripping means G for a given actuator stroke, with resultant savings in overall size of of the tong assembly.

The break out actuator cylinder means B0 are essentially the same as the make up actuator cylinder means MU, just described. Thus, as seen in FIGS. 1 and 3, the break out actuator cylinder means BO includes a pressure cylinder 130, an end ear 131 of which is connected in the case H by a pin 132. A fitting 133 enables the supply and exhaust of pressure fluid to and from the cylinder to cause the piston 134 to extend the rod 135 or allow retraction of the rod, as the slide block 136 is moved along guide rails 140 carried on flanges 142 within the case base 60. This slide block 136 carries a sprocket shaft on which sprockets like the sprockets 114 and 115 are rotatably supported, only the upper sprocket 114 being seen in FIGS. 1 and 3. Since the details of the idler sprocket and slide assembly of the break out actuator cylinder means correspond to those of the make up actuator cylinder means MU, no further specific description is believed to be necessary, except to note that the break out actuator cylinder means acts on the runs of chains 12 between the spinning motor sprocket 78 and the outer ring sprockets 50 to move the outer ring 11 in the opposite direction from the direction in which the outer ring 11 is moved by the make up cylinder means MU, when pressure fluid is supplied to either the make up cylinder 100 or the break out cylinder 130, alternately, as will be later described.

The brake means B, previously referred to, for initially holding the inner jaw carrying ring or member 10 against rotation with the outer ring, in order to set the jaws J in gripping engagement with the pipe, are best seen in FIGS. 2, 5 and 6.

More particularly, the brake means B comprises a brake disc or ring member affixed at its inner periphery by fasteners 151 to a shoulder 152 on the inner ring and extending radially in a horizontal plane, and means for braking engagement with the opposing faces of the brake disc 150, in the form of a plurality of caliper type brake units 153 suitably spaced about and affixed by fasteners 154 to a radial flange 155 formed on the top plate 22 on the tong housing H.

Each brake unit 153, as best seen in FIG. 6, comprises a horizontally split body providing an upper cylinder section 156 having a piston chamber 157 opening towards the upper face of the brake disc 150 and a lower cylinder section 158 providing a piston chamber 159. Each of the piston chambers 157 and 159 contains a piston 160 provided with a suitable annular seal 161, whereby the pistons are adapted to be conduit 165. Since it is desired that the brake units 153 I be simultaneously engaged with thedisc 150 or effectively released, the conduit 165 is connected to each of the brake units, and a common source supplies pressure fluid to all chambers 157 and 1590f all units 153. For example, in FIG. 6, the housing flange 22 is ported at 166 and a supply conduit 167 communicates with the port 166 and with additional supply porting 168 in the housing H to conduct fluid from a source to the brake fluid conduit 165, under the control of means which control the braking action, as will be later described in respect of the control system of FIG. 1 1.

As previously indicated, the reverse stop means RS are provided to limit rotation of the outer or cam ring 11 relative to the inner or jaw carrying ring in a reverse direction to open the jaws J after a pipe joint is made up or broken out. To accomplish this, the reverse stop means permits the outer ring 11 to rotate relative to the inner ring 10 in a selected direction, clockwise for making up joints and counter clockwise for breaking out joints, so that cam surfaces 42M or 42B, respectively, may force the jaws J inwardly to pipe gripping positions, while the brake means B holds the jaw carrying, inner ring 10 stationary, and thereafter the entire gripping assembly G rotates in the selected direction.

vThe reverse stop means RS then functions to prevent rotation of the outer ring 11 relative to the inner ring 10 in the reverse, jaw retracting direction, past the location. at which the jaws are fully retracted, and the cam rollers 35 of the jaws J are in the cam surface 42.

The reverse latch means RS are best seen in FIGS. 2 and 5 through 10. More particularly, the reverse stop means includes a stop member 170 in the form of a ring concentrically mounted upon a support flange 171 which is secured by fasteners 172 to the inner or jaw carrying ring and a companion stop member in the form of a ring 174 on the outer ring 11, herein shown as an upward extension of the bearing ring 31 which provides a race for the ball bearings 30 on which the inner and outer rings 10 and 11 relatively revolve.

In FIGS. 6-10,'it will be-seen that the stop ring 170 is vertically shiftable and has a splined connection 175 with the flange 171' on the jaw carrying ring 10. A suitable number of coiled compression springs 176 are interposed between the stop ring 170 and an opposing portion of the inner ring 10 to provide means for biasing or moving the, stop ring 170 to an upper, normal position, as seen' in FIGS. 6, 7 and 9, and actuator means 177 are provided for shifting the stop ring 170 downwardly to a position, as seen in FIGS. 8 and 10, the upper position being the make up stop position and the lower position being the break out stop position.

The actuator means 177 includes an angularly shiftable ring 178 disposed above the stop ring 170. Bearing means, such as balls 179, are interposed between the actuator ring 178 and the stop ring 170 to facilitate rotation of the latter relative to the former, since the the depressions 43 of stop ring is carried by the revolvable gripping assembly G.

Double acting fluid pressure operated cylinder means, including a pair of cylinders 180, 180, FIGS. 5 and 6, are connected with the actuator ring 178m 181 and with the housing top flange 22 at 182, so as to effect angular movement of the actuator ring 178 in opposite directions relative to the housing.

Meansare provided comprising a suitable number of fixed cams 183 formed on or affixed to the housing top plate 22 byfasteners 184, and a corresponding number of traveling cams 185,.formed on or affixed to the actuator ring 178 by fasteners 186, whereby angular movement of the actuator ring 178 in thedirection of the arrow in FIG. 8 will effect downward movement of the-stop ring 170 from the upper position of FIGS. 7 and 9m the lower position of FIGS. 8 and 10, as indicated by the arrow in FIG. 7. Obviously, movement of the actuator ring 178 from the position of FIGS. 8 and 10 to that of FIGS. 7 and 9, allows the springs 176 to return the stop ring 170 to the normal or upper position. Such actuation will be i further described hereinafter in relation to the control system of FIG. 11.

The stop ring 170, on its outer periphery, has a pair of circumferentially extended stop lugs 170a, herein shown in FIG. 5 as extending substantially 60 about the ring 170 and diametrically spaced. On the end of each lug 170a facing in a counter clockwise direction is a stop face or abutment 170m, which, as will later appear, stops rotation of the outer ring 11 relative to the inner ring 10 when the tong is being used to make up joints and the jaws J are fully retracted. Atthe other end of each lug 170a facing in a clockwise direction, is a face or abutment 170b, which, as will later appear, stops rotation of the outer ring 11 relative to the inner ring 10 when the tong is being used to break out joints and the jaws J are fully retracted.

The reverse stop ring or member 174 cooperates with the ,stop lugs 170a to limit jaw-opening relative rotation of the inner ring 10 and the outer ring 11, and for this purpose, the ring 174 has upper stop lugs 174a and lower stop lugs 174a extending circumferentially on the inner periphery of they ring 174 and arranged so that these lugs are alternately located about the ring 174 at opposite sides of diametrically spaced vertical spaces or slots 174d having an angular extent substantially the same or slightly greater than the angular extent of the respective stop lugs 170a on the stop ring 170, whereby the lugs 170a may move vertically in the slots 174 between the upper and lower stop positions, previously referred to.

When the reverse stop actuator means is conditioned, as seen in FIGS. 5, 6, 7 and 9, for making up joints with the tong, with the reverse stop ring 170 in the upperposition, the upper stop lugs 174a on the ring 174 provide, on their ends 174m facing in a clockwise direction, abutments cooperative with the ends 170m of the stop lugs 170a of the stop ring 170 to stop counter clockwise rotation of the outer ring 11 relative to the inner ring 10 at a location with the jaws retracted, but the lugs 170a will pass above the lower stop lugs 174c (See FIG. 9), so that the outer ring 11 is free to rotate in a clockwise direction relative to the inner ring 10 to close the jaws on and rotate a pipe. Alternatively, when the stop ring 170 is actuated to the lower position of FIGS. 8 and 10, for breaking out joints with the tong, the lower stop lugs 174c on the ring 174 provide on their .ends174b facing in a counter clockwise direction abutments cooperative with the ends 170b ofthe stop lugs 170a of the stop ring 170 to limit clockwise rotation of the outer ring 11 relative to the inner ring 10 at a location at which the jaws J are retracted, but the lugs 170a will pass beneath the upper stop lugs 174a (See FIG. 10), so that the outer rin'gll is free to rotate in a counter clockwise direction to close the jaws J and rotate a pipe. g

In the illustrated tong, three jaws J are shown and the outer ring 11 may move through an arc of approximateis supplied via'a conduit 3008 to drive the motor M in a each diametrically opposed half of the stop ring 174.

heavy shock, say when the jaws are opened at high speed, and the mass of the outer ring 11 is great.

In the use of the tong apparatus thus far described, the motor M is operated, in either direction, to rotate thepipe gripping means G at relatively high speed. To effect initial engagement of the jaws J with a pipe, the brake means B must be applied, to hold the inner, jaw carrying ring 10 against rotation with the outer ring 11 until the gripping of the pipe by the jaws is sufficient to rotate the pipe, at which time self energization of the cam roller system works to assist in the gripping action. After the pipe is gripped, high braking effort is not desirable since the brake must be overcome by the tong motor M. Thus, the brake means B is preferably pressured to an extent determined by torque transmitted through the gripping means to the pipe. In addition, the lock means L should be released automatically when the spinning rnotor M is operated, and the lock means L should be engaged with the spinning motor locking gear 78 when the spinning motor is not operating to lock the spinning motor shaft, and more particularly, to lock the chain sprockets 76, when either of the actuator cylinder means MU or B0 is being operated.

The following is a description of the illustrative tong control system of FIG. 11, whereby the tong is operated as above described.

In order to operate the system, to makeup and break out joints of pipe, a conduit 300 is connected to a suitable pressure source for supplying hydraulic pressure fluid from the source to a main motor control valve MV which has a neutral position and selective positions for controlling fluid flow to the, MOTOR M in either direction, whereby the drive sprocket 78 for the chain means 12 will be driven in a selected direction to drive the gripping means G correspondingly. Thus, when the main motor control valve MV is shifted to the right, as seen in FIG. 11, pressure fluid is supplied to conduit 300M to drive the'motor M in a make up direction, and

when the valve MV is shifted to the left, pressure fluid break out direction, in which case the motor is subjected to full source pressure from conduit 300. In the make up condition of the system, however, the maximum pressure supplied to the motor M via conduit 300M and therefore, the maximum motor torque output, or stall torque, is controlled by a motor torque limiting relief valve 300R connected to the make up conduit 300M by a conduit 301. The maximum pressure in the conduit 301 is adjustable by a variable regulator valve 301R which holds the relief valve.300R closed until the pressure acting on the regulator valve 301R relieves the bias pressure from the relief valve 300R. 1

Operating fluid pressure from conduit 300 is supplied via a conduit 300 to provide pilot pressure to a sequence valve 203$ which is normally closed to shut off the supply of fluid pressure from a supply-conduit 303 to a pilot pressure conduit-304 which leads from the sequence valve 302S to a pilot operated valve 304L which controls the flow 'of pressure fluid from the source conduit 303 via a conduit 305 to one or the other of the conduits'306L and 306U by which the lock means L, previously described, are operated'to lock the motor M or release the'lock. The sequence valve 302$ is controllable or adjustable by means of a variable regulator 302R which determines at what pressure in conduit 302, and hence, conduit 300, the sequence valve will open to. supply pilot pressure to the lockcontrol valve 304L to shift the latter from the normal position as shown to the alternate position to automatically pressurize the lock actuating cylinder 84 and engage V the lock gear 78 with the lock dog 80. Thus, when the motor M stalls when spinning up pipe joints and greater torque is needed to further turn the pipe, the sequence valve 302$, responsive to increased pressure in the motor supply conduit will be operated to allow pressure to shift the lock'control valve 3041. to admit pressure to the lock cylinder 84 via conduit 306L to lock or anchor the chain 12 at the motor M, so that the make up actuator cylinder MU may be operated to finally make up the pipe joint. Onthe other hand, if a joint is to be broken out, the main motor valve MV will be operated to drive the motor in the break out direction and the motor may stall, without initially breaking out the pipe joint, in which case, the sequence valve 302S will also be operated to admit pressure to the lock valve conduit 304 to shift the pilot operated lock valve 304L to the lock engaging position, in which 'fluid flows to the cylinder 84 via conduit 3061., and then the break out cylinder BO may be actuated to break out the joint.

The make up and break out actuators MU and B0, respectively, are controlled by a selector valve 3078 to which fluid is supplied via a conduit 308 from the source conduit 303. V

In the position shown, the selector valve 307$ directs pressure fluid from the conduit to the break out cylinder conduit 3098 to cause extension of the rod 135, whereby the pipe gripping means G will be moved counter clockwise, as fluid returns to the tank from the make up actuator cylinder MU via the conduit 309M.

In the alternate position, of course, the pressure applied in the reverse direction will extend actuator rod 105, and fluid will be discharged back through conduit 3098. Since it is desired that the usual joints be made 'up to a prescribed torque limit, adjustable torque limiting valve means are provided in the pressure conduit leading to the make up actuator cylinder MU. Thus, a normally open valve 308R is interposed between the source of pressure and the actuator cylinder MU and is controlled by an adjustable, pressure responsive relief valve 309R which allows the valve 308R to close, when pressure in line 309M exceeds a selected level. On the other hand to allow full torque application to the pipe when breaking out joints, the conduit 3098 is exposed to the full pressure of source conduit 303.

. The system includes brake control means, as previously indicated, for the brake means B. This control means functions to admit high pressure to the respective piston chambers 157 and 159 to force the pistons 160 toward the brake disc 150 or to reduce the pressure appliedto the brake chambers 157, 159, depending upon whether more or less radial loading of the jaws J into gripping engagement with the pipe is necessary to prevent slipping of the gripping dies during engagement with the pipe and during spinning or make up or break out of the joint, as the case may be.

More particularly, fluid pressure is supplied to the brake chambers 157, 159 via. a conduit 310 leading from the source conduit 303 under the control of a normally open reducing valve 310R which is regulated by an adjustable high pressure relief valve 311R or anadjustable low pressure relief valve 312R, depending upon the pressure of fluid in the supply conduit 300 for the motor M. Thus, a pilot pressure conduit 313 leads from the motor conduit 300 to an adjustable, normally closed relief valve 314R in a conduit 314 leading between the high pressure relief valve 311R and the low pressure relief valve 312R. When the relief valve 314R is closed, as shown, fluid is suppliedthrough'the normally open valve 310R at full source pressure from conduit 303 to apply a high braking force, limited only by the adjustment of the relief valve 311R, even though the motor M is inactive. When the motor control valve MV is opened to operate the tong gripping means, the pressure in motor source conduit 300 will increase as the gripping means encounters resistance upon closure of the jaws on the-pipe. Since the greater the encountered resistance, the greater the force applied by the cam ring 11 on the jaws J to grip the pipe, the pressure in the brake chambers is preferably reduced so that high brake force need not be overcome. The pressure in conduit 313, as it increases, will open the normally closed valve 314R, when the pressure equals the setting of the valve 314R, so that the reducing valve 310R tends to close, reducing the applied brake pressure in chambers 159. Thus, the brake control system is effective to maintain a high brake force to assure that the pipe gripping means securely grips the pipe without slipping thereabout, but when the high braking force is not needed, the pressure is relieved. This characteristic assures longer life of the pipe gripping dies 37 and minimizes damage to the pipe due to skidding of the dies around the pipe.

Additionally, the control system includes means, for selectively operating the reverse stop actuator cylinders 180, only one of which is shown in FIG. 11, for simplicity. The source conduit 303, in the illustrated system, leads to a conduit 315 which is connected to a suitable selector valve 315S. In the position shown, the

valve 315Sdirects pressure fluid to the actuator 180 via a conduit 315M to retract the actuator rod, and thereby position the reverse stop ring 178 in the make up position, as seen in FIGS. 5, 6, 7 and 9, and in the alternate position of the valve 315$, pressure fluid will be supplied via a conduit 315B to shift the actuator rod to an extended position and move the reverse stop actuator ring 178. in its alternate or break out position of FIGS. 8 and 10.

While the main control valve MV for the motor M,

electrical, pneumatic, or hydraulic for remotely operating the system or for integrating the system in an automatic well drilling rig.

From the foregoing, it is believed that no further description of the mode of operation of the present tong is necessary, and that it is now apparent that the invention provides a novel, rugged and versatile power pipe tong.

We claim: v

1. In a power tong: a body having a pipe opening, pipe gripping means in said opening including a pair of relatively rotatable members'rotatably mountedin said body, one of said members having pipe gripping jaws movable from retracted positions into said opening to pipe gripping positions, the other of said members having means cooperative with said jaws to shift the latter to said pipe gripping positions upon relative rotation of said members, .power operated means including a fluid pressure'operated motor for rotating one of said members, and fluid pressure operated brake means for initially holding the other of said members against rotation with said one of said members until said jaws grip the pipe, the improvement comprising means-for supplying pressure fluid to said motor and to said brake means at a pressure determined by the resistance of the pipe to rotation by said motor to increase the pressure supplied to said brake means when the pressure supplied to said motor is low and to decrease the pressure supplied to said brake means when the pressure supplied to said motor is high.

2. In a power tong as defined in claim 1, said brake means comprising a caliper brake unit carried by said body and having opposed fluid pressure actuated brake pistons, and a brake disc carried by said other of said relatively rotatable members and riding between said pistons for engagement therebetween.

3. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and said brake means at a pressure determined by the resistance of the pipe to rotation including a pressure source, conduit means leading from said source to said motor and to said brake means, and regulator means for controlling the pressure of fluid in said conduit means.

4. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and said brake means at a pressure determined by the resistance of the pipe to rotation including a pressure source, conduit means leading from said source to said motor and to said brake means, and pressure regulator means responsive to the pressure of fluid in said conduit 13 means for controlling the pressure of fluid supplied to said brake means.

5. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, and pressure regulator means responsive to the pressure of fluid in said conduits for controlling the pressure of fluid supplied to said brake means,

6. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, and low pressure regulator means responsive to the pressure of fluid in said motor supply conduit for reducing the pressure in said brake supply conduit when the pressure of fluid in said motor supply conduit is high.

7. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, low pressure regulator means responsive to the pressure of fluid in said motor supply conduit for reducing the pressure in said brake supply conduit when the pressure of fluid in said motor supply conduit is high, and high pressure regulator means responsive to the pressure of fluid in said brake supply conduit to limit the maximum pressure of fluid supplied to said brake means.

8. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, low pressure regulator means responsive to the pressure of fluid in said motor supply conduit for reducing the pressure in said brake supply conduit when the pressure of fluid in said motor supply conduit is high, high pressure regulator means responsive to the pressure of fluid in said brake supply conduit to limit the maximum pressure of fluid supplied to said brake means, and including normally closed pressure operated valve means responsive to the pressure of fluid in said motor supply conduit for connecting said brake supply conduit to said low pressure regulator means when the pressure of fluid in said motor conduit reaches a selected high pressure.

9. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, low pressure regulator means responsive to the pressure of fluid in said motor supply conduit for reducing the pressure in said brake supply conduit when the pressure of fluid in said motor supply conduit is high, and high pressure regulator means I responsive to the pressure of fluid in said brake supply conduit to limit the maximum pressure of fluid supplied to said brake means, each of said regulator means being adjustable to enable the application of selected high and low pressures to said brake means.

10. In a power tong: a body having a pipe opening, pipe gripping means in said opening including a pair of relatively rotatable members rotatably mounted in said body, one of said members having pipe gripping aws movable from retracted positions into said opening to pipe gripping positions, the other of said members having means cooperative with said jaws to shift the latter to said pipe gripping positions upon relative rotation of said members, power operated means for rotating one of said members, and brake means for initially holding the other of said members against rotation with said one of said members until said jaws grip the pipe, the improvement comprising means for controlling said brake means responsive to the resistance of said pipe to rotation to reduce the holding force of said brake means when the resistance of said pipe to rotation increases above a selected torque. 

1. In a power tong: a body having a pipe opening, pipe gripping means in said opening including a pair of relatively Rotatable members rotatably mounted in said body, one of said members having pipe gripping jaws movable from retracted positions into said opening to pipe gripping positions, the other of said members having means cooperative with said jaws to shift the latter to said pipe gripping positions upon relative rotation of said members, power operated means including a fluid pressure operated motor for rotating one of said members, and fluid pressure operated brake means for initially holding the other of said members against rotation with said one of said members until said jaws grip the pipe, the improvement comprising means for supplying pressure fluid to said motor and to said brake means at a pressure determined by the resistance of the pipe to rotation by said motor to increase the pressure supplied to said brake means when the pressure supplied to said motor is low and to decrease the pressure supplied to said brake means when the pressure supplied to said motor is high.
 2. In a power tong as defined in claim 1, said brake means comprising a caliper brake unit carried by said body and having opposed fluid pressure actuated brake pistons, and a brake disc carried by said other of said relatively rotatable members and riding between said pistons for engagement therebetween.
 3. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and said brake means at a pressure determined by the resistance of the pipe to rotation including a pressure source, conduit means leading from said source to said motor and to said brake means, and regulator means for controlling the pressure of fluid in said conduit means.
 4. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and said brake means at a pressure determined by the resistance of the pipe to rotation including a pressure source, conduit means leading from said source to said motor and to said brake means, and pressure regulator means responsive to the pressure of fluid in said conduit means for controlling the pressure of fluid supplied to said brake means.
 5. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, and pressure regulator means responsive to the pressure of fluid in said conduits for controlling the pressure of fluid supplied to said brake means.
 6. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, and low pressure regulator means responsive to the pressure of fluid in said motor supply conduit for reducing the pressure in said brake supply conduit when the pressure of fluid in said motor supply conduit is high.
 7. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, low pressure regulator means responsive to the pressure of fluid in said motor supply conduit for reducing the pressure in said brake supply conduit when the pressure of fluid in said motor supply conduit is high, and high pressure regulator means responsive to the pressure of fluid in said brake supply conduit to limit the maximum pressure of fluid supplied to said brake means.
 8. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, low pressure regulator means responsive to the pressure of fluid in said motor supply conduit for reducing the pressure in said brake supply conduit when the pressure of fluid in said motor supply conduit is high, high pressure regulator meanS responsive to the pressure of fluid in said brake supply conduit to limit the maximum pressure of fluid supplied to said brake means, and including normally closed pressure operated valve means responsive to the pressure of fluid in said motor supply conduit for connecting said brake supply conduit to said low pressure regulator means when the pressure of fluid in said motor conduit reaches a selected high pressure.
 9. In a power tong as defined in claim 1, said means for supplying pressure fluid to said motor and to said brake means including a motor supply conduit leading to said motor and a brake supply conduit leading to said brake means, low pressure regulator means responsive to the pressure of fluid in said motor supply conduit for reducing the pressure in said brake supply conduit when the pressure of fluid in said motor supply conduit is high, and high pressure regulator means responsive to the pressure of fluid in said brake supply conduit to limit the maximum pressure of fluid supplied to said brake means, each of said regulator means being adjustable to enable the application of selected high and low pressures to said brake means.
 10. In a power tong: a body having a pipe opening, pipe gripping means in said opening including a pair of relatively rotatable members rotatably mounted in said body, one of said members having pipe gripping jaws movable from retracted positions into said opening to pipe gripping positions, the other of said members having means cooperative with said jaws to shift the latter to said pipe gripping positions upon relative rotation of said members, power operated means for rotating one of said members, and brake means for initially holding the other of said members against rotation with said one of said members until said jaws grip the pipe, the improvement comprising means for controlling said brake means responsive to the resistance of said pipe to rotation to reduce the holding force of said brake means when the resistance of said pipe to rotation increases above a selected torque. 